Expansible bit.



A. B. JENNINGS.

EXPANSIBLE BIT.

APPLIOATION FILED AUG.14, 1909.

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ARCHER- B. JENNINGS, OF WALLINGFORD, CONNECTICUT.

EXPANSIBLE BIT.

To all whom it may concern:

Be it known that I, Anorrnn B. JENNINGS, a citizen of the United States,residing at VVallingford, in the county of New Haven and State ofConnecticut, have invented a new and useful Improvement in ExpansibleBits; and I do hereby declare the following, when taken in connectionwith the accompanying drawings and the letters of reference markedthereon, to be a full, clear, and exact description of the same, andwhich said drawings constitute part of this specification, andrepresent, in-

Figure 1 a front or plan view of an ex pansible bit embodying myinvention. Fig. 2 a sectional side view of the same. Fig. 3 a rear viewof the cutter detached. Fig. 4; a side view of the adjusting screwdetached. Fig. 5 a side view of a bit illustrating a modified form of myinvention.

This invention relates to an improvement in expansible bits, and bits ofthis type in which a sliding cutter is adapted to be adjusted by a screwmounted in the head and working in a rack formed on one surface of thecutter. I

The object of the invention is to provide a bit in which the cutter maybe adjusted by a screw, in which the cover is readily and securelyclamped in its adjusted position, and a cutter which is cheap tomanufacture; and the invention consists in the construction hereinafterdescribed and particularly recited in the claims.

In carrying out my invention the bit-head 2 is formed with the usualgimlet screw point 3 and scoring lip 1. One side of the head 2 isflattened, and in this flat surface is a wide transverse groove 5, andin the bottom of this groove is a semi-circular channel 6 formed at itscenter with a semi-circular rib 7. The lower wall 8 of the groove isalso preferably undercut. Arranged in this groove 5 is an adjustablecutter 9 of a length corresponding to the size of the hole to be cut.The upper edge of this cutter has a rear beveled edge 10 adapted to meshwith a screw 11 which is seated in the channel 6, the central portion ofthe screw being cut away to clear the rib 7 which serves to hold thescrew against longitudinal movement. The outer upper edge 12 of thecutter is beveled the reverse of the beveled rack 10, and coacting withthis surface of the cutter is a clamping plate 13 located in theSpecification of Letters Patent.

Application filed August 14, 1909.

Patented Mar. it, 1910. Serial No. 512,838.

upper portion of the groove 5 and held in place by a screw 14 whichpasses through it and into the head 2, and by which the clamping platemay be crowded against the cutter 9 so as to hold it when adjusted. Byloosening the screw 14 the cutter may be adjusted by means of the screw11. While I prefer to form the transverse groove 5 of uniform depth assuch a cut could be made more conveniently, the upper portion of thegroove may be of less depth than the lower portion, as shown in Fig. 5,so as to form two steps 15 and 16. At the junction of these steps is achannel 17 to receive the screw 11. The cutter is formed in the same wayas above described, but the clamping plate 18 must have its lower edge19 bowed to clear the screw 11 to engage with the upper forward edge ofthe cut-ter so as to clamp the cutter in its adjusted position. The samecutter may be used in both forms of my invention.

I claim 1. An expansible bit comprising a head having a transversegroove, a transverse channel in said groove, a screw mounted in saidchannel, a cutter arranged in the lower portion of said groove andhaving its upper rear edge beveled and provided with a rack to engagewith said screw, the upper outer edge of said cutter also beveled, and aclamping plate located in the upper portion of said groove and adaptedat its lower edge to cooperate with the outer upper edge of the cutterwhereby the cutter may be clamped in its adjusted position.

2. An expansible bit comprising a head having a transverse opening ofuniform depth, a semi-circular channel in said groove, a screw mountedin said channel, a cutter mounted in the lower portion of said grooveand formed at its upper rear face with a rack to engage with said screwand with its upper outer face beveled, and a clamping plate in the upperportion of said groove and having its lower edge to cooperate with thebeveled upper outer edge of the cutter.

In testimony whereof, I have signed this specification in the presenceof two subscribing witnesses.

ARCHER B. JENNINGS.

Witnesses:

FREDERIO G. EARLE, CLARA L. WEED.

